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Bulk Density of Long- and Medium-Grain Rice Varieties as Affected by Harvest and Conditioned Moisture Contents¹

¹Published with the approval of the Director, Agricultural Experiment Station, University of Arkansas. Mention of a commercial name does not imply endorsement by the University of Arkansas. ²Research associate, professor, graduate research assistant, and extension agricultural engineer, respectively, Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR 72701. ³Corresponding author. Phone: 501/575 2841. Fax: 501/575 2846. E-mail: tsiebenm@saturn.uark.edu

The effect of harvest and conditioned moisture contents (MC) on bulk density (BD) of rough, brown, and white rice was determined for several long- and medium-grain rice varieties harvested from different Arkansas locations. The results indicated that harvest MC (HMC) significantly affected the BD of freshly harvested and conditioned rough rice. Higher HMC levels resulted in lower BD levels for rough rice over the conditioned MC range from 11 to 29% (wb). There was a strong linear relationship between rough rice BD and conditioned MC for a given HMC. The harvest location had a more pronounced effect on rough rice BD of long-grain varieties than of medium-grain varieties. The BD of brown and white rice was less dependent on harvest location and conditioned MC than the BD of rough rice. Rice harvested at low MC level (≈13%) gave a higher BD for both brown and white rice than that harvested at higher MC levels. Medium-grain varieties showed a higher BD for brown and white rice than did long-grain varieties.